Urticaria papular y sus agentes causales en Colombia / Papular urticaria: A review of causal agents in Colombia

Resumen La urticaria papular es una enfermedad alérgica causada por la picadura de insectos, la cual predomina en el trópico. El objetivo de esta revisión fue profundizar en sus aspectos epidemiológicos e inmunológicos, particularmente con base en datos publicados en Latinoamérica. Se hizo una revisión no sistemática mediante la búsqueda electrónica de artículos sobre la epidemiología de la urticaria papular, las características entomológicas de los agentes causales y los mecanismos inmunológicos asociados. Según los diversos reportes de centros médicos de Latinoamérica la urticaria papular es frecuente; el único estudio de prevalencia publicado indica que afecta a una cuarta parte de los niños escolares de Bogotá. Hay información sobre la relación causal entre la exposición domiciliaria a la pulga, la pobreza y la urticaria papular en Bogotá, una ciudad representativa de las altitudes andinas. No hay estudios que indaguen directamente sobre los insectos causales en zonas cálidas, aunque se sospecha clínicamente de los mosquitos Aedes aegypti y Culex quinquefasciatus. En cuanto a su patogenia, se destaca la participación de mecanismos celulares que involucran las células colaboradoras Th2, lo cual explica que sea una condición de hipersensibilidad retardada. El papel de la inmunoglobulina E (IgE) en la urticaria papular no está tan claro. Se desconocen los antígenos derivados de los insectos que causan la enfermedad, aunque se plantea que existen moléculas comunes de reacción cruzada entre los insectos, tales como el alérgeno Cte f 2 en la pulga, y sus homólogos en los mosquitos. La urticaria papular es una condición frecuente en Latinoamérica que debe investigarse en profundidad. La caracterización inmunológica de los componentes moleculares que causan esta condición puede resolver interrogantes sobre su etiología y su patogenia.

Abstract Papular urticaria is a chronic allergic reaction induced by insect bites, which is common in the tropics. The objective of this review was to deepen on epidemiological and immunological aspects of this disease, focused on data published in Latin American countries. We conducted a non-systematic review of the literature through electronic search on the epidemiology of papular urticaria, the entomological characteristics of the causative agents and associated immunological mechanisms. Several reports from medical centers suggest that papular urticaria is common in Latin America. Only one epidemiological survey designed to estimate prevalence of papular urticaria has been published, reporting that about a quarter of children under six years of age is affected by this condition in Bogotá. There is evidence on the causal relationship among exposure to indoor fleas, poverty and papular urticaria in Bogotá, a representative city of the Andean altitudes. Information about causal insects in tropical warmer areas is scarce, although from clinical reports Aedes aegypti and Culex quienquefasciatus appear to be the most common. Th2 cellular-mediated mechanisms are involved in its pathogenesis, which explains its delayed hypersensitivity. The role of immunoglobulin E is not clear in this disease. Insect-derived antigens directly involved in papular urticaria etiology are unknown. However, it is possible that common molecules among causal insects mediate cross-reactive reactions, such as Cte f 2 allergen, found in cat fleas, and its counterparts in mosquitoes. Papular urticaria is a frequent disease in Latin America that should be further investigated. Immunological characterization of the molecular components that cause this condition may solve questions about its pathogenesis.

Teste de desencadeamento alimentar oral na confirmação diagnóstica da alergia à proteína do leite de vaca / Oral food challenge test to confirm the diagnosis of cow's milk allergy

OBJETIVO: Verificar a prevalência de alergia à proteína do leite de vaca em crianças com sintomas atribuídos à ingestão do leite de vaca. MÉTODOS: Foram estudadas 65 crianças com sintomas atribuídos à ingestão do leite de vaca. A definição diagnóstica ocorreu após teste de desencadeamento alimentar oral aberto, realizado no mínimo 15 dias após dieta de exclusão e ausência de sintomas, com período de observação de até 4 semanas após o teste. Considerou-se caso (alergia à proteína do leite de vaca positiva; n = 35) criança com reaparecimento do sintoma que motivou a realização do teste, e comparação (alergia à proteína do leite de vaca negativa; n = 30) aquela sem sintomas após o período de observação do teste. RESULTADOS: A mediana de idade foi 5 meses (P 25-75 por cento 2-9 meses) no grupo caso e 7 meses (P 25-75 por cento 4-11 meses) no grupo comparação (p = 0,05). O teste não confirmou alergia à proteína do leite de vaca em 46,8 por cento dos pacientes com sintomas atribuídos à ingestão de leite de vaca. Reação tardia ocorreu em 77,1 por cento (27/35) dos casos com teste positivo, sendo 18/27 na primeira, 3/27 na segunda e 6/27 na terceira semana de observação. Encontrou-se associação estatística significante entre manifestações cutâneas e teste positivo (p = 0,04), mas não com sintomas digestivos e respiratórios. CONCLUSÃO: Os resultados corroboram a necessidade do teste de desencadeamento alimentar oral para determinar os pacientes que realmente têm alergia à proteína do leite de vaca e se beneficiarão com dieta de exclusão de leite de vaca.

OBJECTIVE: To determine the prevalence of cow's milk protein allergy in children with symptoms attributed to cow's milk intake. METHODS: Sixty-five children with symptoms attributed to cow's milk intake were studied. Diagnosis was established after an open oral food challenge test carried out at least 15 days after an elimination diet and absence of symptoms, with a follow-up period of up to 4 weeks after the test. The children who remained asymptomatic after this period were considered negative for cow's milk protein allergy (n = 30), while those whose symptoms reappeared were considered positive (n = 35). RESULTS: The median age was 5 months (P 25-75 percent 2-9 months) in the case group and 7 months (P 25-75 percent 4-11 months) in the comparison group (p = 0.05). The test did not confirm cow's milk protein allergy in 46.8 percent of the patients with symptoms attributed to cow's milk intake. A delayed reaction occurred in 77.1 percent (27/35) of the cases testing positive, 18/27 in the first week, 3/27 in the second week, and 6/27 in the third week of follow-up. A statistically significant association was found between cutaneous manifestations and positive test result (p = 0.04). However, there was no association with digestive and respiratory symptoms. CONCLUSION: Our results confirm the need of an oral food challenge test to determine which patients really have cow's milk protein allergy and may therefore benefit from a diet free of cow's milk.

DTH responsiveness of HIV-infected Thai adults.

A study was carried out in Thailand to determine the frequency of reactivity to delayed-type hypersensitivity (DTH) skin tests used for the staging of HIV patients in the United States. A four-antigen panel which included tetanus toxoid (1:10), Candida (1:10), mumps and Trichophyton antigens was assessed in 221 adult subjects from across the full immunological spectrum of HIV disease. Complete anergy was found in 38 per cent of 73 subjects with CD4 counts of 0-200 cells/ml and in 6 per cent of 78 subjects with 201-400 cells/ml. Partial anergy (response to 1 of 4 antigens) was found in 26 per cent of the 0-200 cell/ml group and decreased progressively with increasing CD4 cell count. Results suggested that a 3-member recall antigen panel would provide nearly all the clinically useful information gained by the more standard 4-member panel. In conclusion, DTH skin testing was confirmed to provide a method of assessing the integrity of cellular immune function of HIV-infected Thai adults which correlated with disease progression.

Waning of post vaccinial allergy after neonatal BCG vaccination.

Tuberculin sensitivity or post vaccinial allergy (PVA) is widely used as an indicator of successful BCG vaccination. The protection conferred by BCG vaccination, the duration of post-vaccinial allergy and the relationship between the two remain a subject of controversy. The present study was conducted with the aim of finding the duration of PVA and evaluate the need for revaccination. One thousand newborns were given BCG under controlled conditions and followed up for PVA by serial PPD (5TU) injection at 3, 6, 12, 24, 30 and 36 months. An induration of 5 mm or less was recorded as negative and no subsequent testing was done. At 3 month, all the infants were given PPD and 95.3% showed a positive response. The positivity rate declined significantly (p < 0.01) to 19% by 3 years of age. A statistically significant (p < 0.01) fall in the mean PPD induration size was also noted. At 3 months, the mean induration size was 10.68 mm but by 3 years it had decreased to 3.86 mm. The distribution of PPD size also showed that with the increase in age, there was a shift towards the smaller size. At 3 years of age, none of the children had an induration of more than 10 mm. The booster effect due to repeated PPD testing was seen in a small percentage and only at 6 and 12 months test. Subsequently no increase in PPD induration was noted. Sex of the child did not influence the PPD induration size significantly (p > 0.05). At 3, 6 and 12 months of age, significant correlation between BCG lesion and PVA was noted, the co-efficient of correlation being 6.(ABSTRACT TRUNCATED AT 250 WORDS)

Reacción tuberculínica en niños de uno a cuatro años de edad vacunados con BCG. Lambayeque-Perú / Tuberculinic reaction in BCG vaccinated children aged one to four years

Considerando las discrepancias existentes sobre la calidad de la vacuna BCG aplicada en nuestro medio y la utilidad del PPD como método de diagnóstico de la infección tuberculosa, se realizó la presente investigación con los objetivos de determinar la prevalencia de la reactividad tuberculínica en niños de 1 a 4 años de edad, vacunados con BCG y evaluar indirectamente la utilidad del PPD. Se efectuó un muestreo sistemático en toda la población de la ciudad de Lambayeque, captándose un total de 569 niños de 1 a 4 años de edad becegeizados, aplicándoseles PPD 2 UT según pautas estandarizadas de la OMS/OPS. Los resultados nos indican un alta prevalencia de respuesta negativa al PPD: 90 por ciento del total de niños. No existe diferencia significativa según grupo etáreo, hacinamiento o grado de nutrición en la respuesta tuberculínica. Se plantea la revaloración del criterio internacional oficial sobre la utilidad del PPD como método diagnóstico de infección tuberculosa natural, dado que la vacuna no ocasiona distorciones en nuestro medio, y por otro lado efectuar estudios para determinar la razón de la alta negatividad de respuesta en niños vacunados, que indicarían mala calidad de vacuna BCG aplicada o deficiencias de respuestas inmunológicas en nuestra población infantil

Estimativa da prevalência de infecçäo tuberculosa em escolares vacinados com BCG, por meio de método de Bhattacharya / The determining of the prevalence of tuberculosis infection among vaccinated school-children by Bhattacharya's method

Em populaçöes muito afetadas por reaçöes tuberculínicas inespecíficas, o teste tuberculínico padronizado, via de regra, superestima a infecçäo tuberculosa. A bem sucedida aplicaçäo do método de Bhattacharya (método gráfico para a decomposiçäo de uma distribuiçäo de frequências em componentes normais) na análise de resultados do teste em populaçäo contaminada por infecçöes atípicas sugeriu seu uso nos resultados obtidos em populaçöes vacinadas com BCG. Assim, na análise dos resultados de dois inquéritos tuberculínicos realizados na cidade de Säo Paulo, SP(Brasil), em 1982 (escolares vacinados entre o segundo e o sexto ano de vida), e em 1988 (escolares vacinados no primeiro ano de vida), foi possível a caracterizaçäo e quantificaçäo da componente normal devida à infecçäo natural em cada uma das misturas. Na populaçäo de 1982 o diâmetro médio das reaçöes foi de 17,40 mm com desvio padräo 3,72 mm, e a proporçäo de infectados foi de 7,71 por cento contra 4,85 por cento nos näo vacinados; na populaçäo de 1988, o diâmetro médio foi 17,00 mm com desvio padräo 4,67 mm, e a proporçäo de infectados foi de 4,14 por cento contra 4,48 por cento nos näo vacinados. Concluiu-se que o método permite estimar a prevalência da infecçäo tuberculosa em populaçöes com alta cobertura vacinal, desde que a vacina tenha sido aplicada no primeiro ano de vida

Esporotricosis. Estudio comparativo de los antigenos miceliar y levadura de S. schenckii mediante pruebas cutaneas. / Sporotrichosis. Comparative study of micelle antigens and yeast or S. schenckii by means of skin tests

Se estudian 952 individuos mediante pruebas cutaneas de hipersensibilidad retardada para esporotricosis. Se incluyen 78 pacientes con dicha entidad, 82 con micosis distintas de esporotricosis, 100 con dermatosis no micoticas, 23 con sospecha de leishmaniasis, 150 estudiantes sanos de la Facultad de Medicina y 519 individuos asintomaticos de diferentes zonas geograficas de los departamentos de Antioquia y Bolivar; se hace una comparacion entre 2 antigenos metabolicos de S. schenckii, a saber: miceliar y levadura; los resultados demuestran el valor diagnostico de las pruebas cutaneas en esporotricosis, su sensibilidad que supera la del cultivo y su alta especificidad